Heart Rate Variability as a Predictor of Outcome in Acute Stroke

Background and purpose: Significant number of acute stroke patients may experience stroke-in-evolution, which is often associated with a worse outcome. We hypothesized that heart rate variability (HRV) analysis is an early outcome predictor in non-atrial fibrillation (non-AF) stroke patients. Methods: The study sample comprised 2 groups of individuals with acute stroke and recruited from the patient population Chelyabinsk Regional Clinical Hospital. First group included 23 patients (mean age 56,5±3,4 years) with fatal outcome (mortality). Second group consisted of 101 patients (mean age 57,0 ±1,5 years) with a favorable outcome – clinical recovery. In the control group after neurological examination were included 77 people (36 men and 41 women) who had no clinical and instrumental sighs of cerebral and cardiac pathology (mean age 54,1±0,8 years). By sex and age group was comparable with the primary. We recorded high-resolution (1000Hz) electrocardiograms of 5-minute duration that were digitized and stored for the off-line analysis (CAP-RC-01 "Micor" software package). Time and frequency domain HRV measures were derived for the filtered and rectified ECG data for each patient. Clinical and HRV profiles were compared among patients who died or survived. Results: Two variables low-frequency (LF) spectral power and very low-frequency (VLF) spectral power correlated with mortality. After adjustment for mechanical ventilation and vasopressor administration, LF, VLF, and Triangular index of RR interval (TINN) correlated with mortality. On multiple regression analysis weighed for mechanical ventilation and vasopressor administration, LF spectral power was a factor that independently predicted mortality. Conclusions: High-resolution HRV analysis is a useful predictor of the outcome in patients with acute stroke and proved to be a reliable predictor of unfavorable cardiac complications and other known manifestations of autonomic failure associated with stroke.